You can find reverse EM's
Some are "through EM's" which means they can be used in two directions as a "shuttle"
Some also have spring returns which can in some cases be used to keep the pole in a set position.
Some even have dual poles with a centre position at zero voltage.
I would suggest you look a little further into "electro magnet arduino" on google or such.
PieterP's suggestion is also an excellent one.